Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Description & Operation: Description
The Engine Coolant Temperature Sensor (ECTS) is located in the cylinder block and cylinder head, and measures the temperature of the engine coolant.
The thermistor of the cooling water temperature and resistance has a Negative Temperature Coefficient (NTC) where the resistance decreases when the temperature rises and the resistance increases when the temperature decreases.
The ECTS # 1 mounted on the cylinder head measures the coolant temperature from the engine, and the ECTS # 2 mounted on the cylinder block measures the coolant temperature entering the engine. The ECTS # 1 and the ECTS # 2 deliver the cooling water temperature to the ECM (Engine Control Module), which delivers the signal to the Thermal Management Module valve (TMM).
The TMM that receives the signal controls the flow of coolant to adjust the coolant temperature. In addition, the ECTS calibrates the fuel injection quantity and the ignition timing based on the information of the cooling water temperature to prevent the engine failure and an engine-hunting during a cold start test.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.